I'm winterizing my (new to me) 1990 PS190. On previous boats I have pulled the water inlet hose at the hull and sucked the antifreeze from there. After searching this forum I see a lot of people attaching the hose at the raw water pump, bypassing the transmission cooler. I would prefer to do it this way as its easier to get at and doesn't break the seal at the hull, however I can imagine there is some water lying in the transmission cooler lines.

It is best not to bypass the trans cooler. Even though you never put the trans into gear, the pump is still turning and the cooler should still be utilized. I have a 1 1/4" hose (permanently attached to the tub I use) that I connect to the trans cooler inlet. Easy to get to and effective.

I'm winterizing my (new to me) 1990 PS190. On previous boats I have pulled the water inlet hose at the hull and sucked the antifreeze from there. After searching this forum I see a lot of people attaching the hose at the raw water pump, bypassing the transmission cooler. I would prefer to do it this way as its easier to get at and doesn't break the seal at the hull, however I can imagine there is some water lying in the transmission cooler lines.

Which method is recommended?

I suspect that the transmission cooler is downstream from the pump on your boat. Attaching to the RW inlet wouldn't bypass the cooler.

As to the transmission cooler lines, there are none that contain water. Transmission oil is circulated through the cooler. The water path out of the RW pump through the cooler is just a straight 1 1/4 inch shot. The cooler is vertical...should self-drain promptly.